1. Field of the Invention
The present invention relates generally to pile driving apparatus. More specifically, the present invention relates to an improvement in pile driving apparatus whereby a noncircular pile may be centered and rotated.
2. Description of the Art
Pile driving apparatus have long been used in the construction industry for installing foundations and the like. All varieties of piles are employed in this regard, exemplary of which are wooden, steel, and concrete piles. Likewise, the piles may have various cross-sectional configurations; and, for purposes of the present invention, these may be divided between circular and noncircular geometries. Those of interest herein are noncircular, and include, for example, square, rectangular, triangular, octagonal, I and T.
Conventional pile driving apparatus are comprised of a lead, which is positioned adjacent the location for driving the pile by a crane or other suitable device. The lead extends upwardly from the foundation area to provide a carriage for a pile driving hammer. A pile is positioned at the foundation site beneath this hammer, and the latter impacts upon the former to drive it into the foundation area.
A substantial improvement in the operational efficiency of pile driving apparatus has been made by the present inventor, in regard to those inventions disclosed and claimed in U.S. Pat. No. 3,827,508. These inventions concern a pile positioning apparatus (hereinafter referred to as a "pile guide") which serves to properly position the pile beneath the pile driving hammer. Prior to the invention of the pile guide, it was necessary to manually position the upper end of the pile within the helmet of the hammer. This process was time consuming, difficult, and oftentimes dangerous. The pile guide simplifies this procedure in the sense that it urges the pile into proper engagement with the helmet and is controlled by the crane operator from his remote position. For further details on the structure of these pile guides, reference is made to the aforementioned United States patent, which is incorporated herein and relied upon.
Pile driving apparatus also conventionally include a foot yoke located proximate the lower end of the lead. A foot yoke, and its associated structure, serves to position the lower end of a pile at the proper location and guide the same as the pile is being driven into the foundation area.
There have been many refinements in the structure utilized for pile driving apparatus over the years. Accordingly, these tasks have been materially simplified and made much more efficient. However, while the driving of a single pile has been so improved, most construction jobs require the driving of a series of piles which must be carefully located along a given line; usually, a straight line. Therefore, the lead must be repositioned by the crane to consecutive locations corresponding to the overall foundation area. This may be further complicated if the lead is carried on a locomotive crane or a barge-mounted crane, where mobility is not only restricted to a great degree but repeated movement of the crane is highly undesirable.
This problem is exacerbated when piles having a noncircular cross-section are employed. Although the lead may be moved by the crane to a limited extent from one location to the next and the hammer properly positioned over the pile, for any cross-section but circular the pile will have the wrong cross-sectional orientation. This is, obviously, unacceptable.
To date, three solutions to this problem have been proposed and employed in the installation of noncircular piles. The crane and lead are moved. The lead itself is rotated. The pile has been manually rotated and restrained by a specially-constructed template, which is otherwise independent of the pile driving apparatus. None of these, nor a combination of them, is totally satisfactory.